Propeller



Sept. l0, 1940.

R. E. LORENZEN PROPELLER Filed Sept. C50, 1957 0' ff @t je PatentedSept. 10, 1940 i UNITED STATES PATENT OFFICE 3 Claims.

This invention relates in general to a propeller for use with airplanes,boats, fans and the like, and has more'particularA reference to apropeller with adjustable blades adapted to be easily set at any desiredangle with respect to the hub for varying the pitch thereof.

An important object of the invention is in the provision of a propellermade of plastic material and cast in one piece.

A further object of the invention is in the provision of blades whichvary their contour from the inner to the outer end so that they can beeasily adjusted and set at various different pitches with respect to thehub or holder.

A still further object of the invention is in the provision of anadjustable propeller having blades .adapted to be yieldingly set in anydesired position in the hubrprior to the attachment of the hub to itsrotating shaft.

A still further object ofthe invention is in the provision of a clampinghub or holder, and for a plurality of blades in which the blades aresparately adjustable to vary their pitch and each y Fig. 1 is aperspective view of a two-bladed` propeller attached to the end of ashaft;

Fig. 2 is a sectional view of the hub or blade holder; t

Fig. 3 is a detail of the attached end of one of the blades;

Fig. 4 is a section taken on the line 4-'4 of Figure 3;

Fig. 5 is a perspective illustrating the method of setting the blades atdifferent pitches;

Fig. 6 is' an enlarged view of one of the blades and the holder showingthe pitch mark on the blade; and

Fig. 7 is a plan view of a three-blade holder.

This invention relates particularly to a propeller with adjustableblades at the same or difsmall or model airplanes in which it is desiredtov vary the pitch of the propeller blades under different conditions,and for 'motors of different sizes. Howevenadjustable propellers of thistype for boats, out-board motors, fans and also for larger aircraft.

It is -contemplated that the separate blades will be made of plasticmaterial such as Bakelite, or other condensate products, which are bothlight 5 and strong, and for propellers of fixed pitch the t blades andcentral mounting may be cast or formed integrally of the same materialrequiring no separate hub. The blades may also be made of wood .orlight-Weight material for adjustment, 10 as herein set forth.

Referring now more particularly to the drawing, a two-bladed propelleris shown in Figure 1, having separate blades II) mounted at the ends ofa hub or holder comprising two similar parts l5 II which when placedtogether form opposite semi-circular hubs with transverse attachmentbores I2 through which a fastening member I3 .may be inserted forrigidlyattaching the propeller to a shaft I4, or other rotating part.

Each of the blades is formed near its inner end with a straight portionI5 of the uniform size at the extremity of which is a flange I6preferably rounded atv the outer edges. At the inside of the hub membersis a straight portion I 1 at 25 the inner end-of which is a curvedgroove or depression I8 adapted to receive the portions I5 and I6respectively of the blade. Longitudinal steel wires I9, or othersuitable reinforcing struc- A tures, such as I9, as indicated in Fig. l,may be 30 molded or cast in the blades.

'At the outer extremities ofthe hub sections are grooves 20 for settingspring rings 2l therein. In assembling a propeller, the spring rings arecommonly placed on the attachment ends of the 35 blades, the blades willride in the hub parts Il and the spring rings 2l are slipped up over theends and into the grooves 20, thereby yieldingly holding the hub halvestogether and the blades clamped loosely therein.

It is to. be understood that the blades vary in shape or contourthroughout the length of the blade. That is, the pitch of the blade isincreased from the inner portion outwardly. By providing each blade withseparate marks designated A, B, 45 C, D and .the like, which relate. tovariations in curvature on the pitch of the blade, the blade itself maybe set in its holder by applying to the flat or inner side of the bladean angular setting plate or setting device 22 referred to an adjacent 50plane surface, or as shown in Fig. 5, the assembled propeller may bereferred to rectangular cci-ordinates :ii-z, zl-zf, one of which isprovided with special graduation's a, b, 'c, d, etc., referred to thelength of the blade from the common axis,

and in order to set a blade at any desired pitch, an angular settingdevice 22 is placed upon a plane surface inv any desired settingposition with one edge to engage the inner face of a blade and byadjusting the blade in its holder it will conform to the contact surface23 of the setting de-` vice at that position. 'I'hus the position of anyblade may be adjusted in its holder corresponding to the pitch desired,and each of the blades may be set correspondingly, or the blades may begiven different pitches in the same holder. The holding spring rings 2|permit dierent adjustment of the blades in the holder, and whenv thepropeller 'thus set is applied to a shaft for rotating it, the fasteningdevice I3 clamps the holder halves Il tightly against the ends of theblades, holding them iirmly in their set position.

It is also contemplated that a multi-blade holder 25, as shown in Figure7, consisting of similar upper and lower clamping plates securedtogether by fastening screws 26 may be employed for lpropellers havingmore than two blades. The separate blades may be individually adjusted,and clamped in place by the holder. y

In this manner a simple adjustable propeller may be produced, which iscapable of easy ad- Justment and variation,v the blades being sep-`arately variable for -adjustment of pitch and being releasably held forfirmly clamping them in any position in which they are set prior totheir attachment to the shaft or other means by which they are rotated.l

I claim:

1. In an adjustable propeller having blades rotatable in a hub about alongitudinal axis, and the pitch of the blade increasing as'its distancefrom the` hub of the propeller, the method ofv varying and setting thepitch of the blade which consists in providing the blade on one surfacewith a series of graduations at various distances from thelhub of thepropeller and adapted to be referred to a plane surface upon whichY thepropeller is placed, such that an angular setting device may be insertedbetweenY the surfaces of the plate and thesurface upon which the propellerv is supported at one of the graduations, and the blade rotatedabout the longitudinal axis to conform Athe surface to the edge ofthesetting device depending upon its position with respect to the pitchmarks of the blade on the setting surface.

2. Ank adjustable propeller having blades mounted to turn about alongitudinal axis in a hub, the pitch of each ,blade varying as itsdistance from the hub, and having graduations on the blade indicatingdistance from the hub; and an angular setting device having one surfaceto engage a reference surface adjacent the blade and another surface toengage the surface of the blade at various distances from the hub inaccordance with the graduations for setting the pitch of the blades.

3. An adjustable propeller having separate blades, a hub havingseparable plates in which the blades are rotatable about longitudinalaxes,

- desired pitch, and means for rmly clamping the hub plates together tohold the blades as set.

